As of January 1, 2018, the standard mileage rates for cars, vans, pickups or panel trucks are:
Remember that employers are required to reimburse employees for work-related mileage, other than the usual commute to and from work. Employers may choose to pay rates lower than the IRS standard if the chosen rates fully compensate the employee for travel-related costs (including fuel, insurance, repairs, and depreciation). However, payment of the IRS standard rates will be deemed reasonable and sufficient reimbursement as a general rule.
You can find the current rates at: https://www.irs.gov/newsroom/standard-mileage-rates-for-2018-up-from-rates-for-2017.